John Calvin Commentary Jeremiah 49:38

"and I will set my throne in Elam, and will destroy from thence king and princes, saith Jehovah." — Jeremiah 49:38 (ASV)

He confirms what I have just referred to regarding their consumption; but at the same time, he adds that God would be the avenger in such a way, as if His tribunal were set up in that land. He threatens that He would destroy the king and the princes; and this, as I have explained, was the consumption. For though some individuals would remain alive, the name of the people would not survive; the whole race as such would become extinct.

But these words should be noted—that God would set up His throne. God is said to set up His throne when He rules; but His kingdom is not always to be understood in a positive sense.

God is properly said to rule or reign among the faithful, whom He governs by His Spirit. So God’s kingdom begins and has its origin when regeneration takes place. But sometimes, as I have already said, God is said to reign among His enemies, as we have seen regarding the Egyptians. He then set up His throne when He executed His recorded judgment on the Elamites, for though the Elamites were blind, God’s power was nevertheless made truly evident, and by the effect He proved that He was the King of that people whose wickedness He punished with such severity. In short, as God is said to be silent, to sleep, or to lie down when He does not execute His vengeance, so in this place He is said to set up His throne when He acts as a Judge.